A comparison of two methods for estimating average exposure to power-frequency magnetic fields.
Wenzl TB; Kriebel D; Eisen EA; Moure-Eraso R
Appl Occup Environ Hyg 1995 Feb; 10(2):125-130
The results of power frequency magnetic field (MF) measurements with two types of instruments were compared. Estimated exposure averages computed from spot measurements (hand held meter) were compared with average MF exposures derived from data recorded by a datalogging three axis personal monitor worn by a group of machining and assembly workers. The investigation was performed at an automobile transmission facility, in operation since 1943, which employed about 8,000 people. Electrical power was supplied to machine tools via a 440 volt three phase wiring system. It was possible to estimate fractions of time spent at each of several work stations and to measure the MFs at both head and waist for 57 workers. The other 24 workers were in maintenance and other jobs without fixed work stations. Both calculated daily weighted averages (DWAs) and dosimeter measures of central tendency of MF strength showed a wide range of values, reaching two orders of magnitude. Closer agreement was found between the DWA and the datalogger's geometric mean than between the DWA and the arithmetic mean. Demagnetizers were unexpectedly found to be an important source of exposure in some of the jobs. For one cluster of demagnetizers which influenced exposures up to 15 meters away, the power law exponent for falloff with distance was estimated with measurements in four directions.
NIOSH-Publication; NIOSH-Grant; Cancer; Radiation-exposure; Dosimetry; Magnetic-fields; Electromagnetic-radiation; Radiation-hazards; Epidemiology; Risk-factors; Radiation-measurement; Occupational-exposure
Work Environment University of Lowell One University Ave Lowell, MA 01854
Applied Occupational and Environmental Hygiene
University of Massachusetts Lowell, Lowell, Massachusetts